We continued to investigate the risk of hepatitis C transmission by one lot of intramuscular immune globulin(IG) containing a low level of HCV RNA but devoid of anti-HCV. In collaboration with the CDC, ca. 200 recipients of the 10 lot in two health clinics were retrospectively evaluated. Anti- HCV was found positive in 3.1% recipients. HCV RNA testing, genotyping, sequencing and phylogenetic analyses were subsequently performed. However, our results fail to establish a causal relationship between the 10 lot and its recipients. We also continued to perform HCV RNA testing in IGIM lots not yet subjected to validated viral clearance procedures in their manufacture. In addition, we participated in three collaborative studies with WHO/NIBSC to establish international standards for HCV RNA, anti-HAV, and anti-HCV reagents. A specific nested PCR procedure to detect human Parvovirus B 19 DNA in plasma derivatives has been developed. The effects of different manufacturing procedures on the levels of B 19 DNA in factor VIII concentrates are being evaluated.